1. Field of the Invention
The present invention relates to an optical film, and a polarizing plate and a liquid crystal display device that use this optical film.
2. Description of the Related Art
An optical film such as a cellulose acylate film has been used in various liquid crystal display devices as an optical member of the liquid crystal display device, for example, a support of an optical compensation film, a protective film of a polarizing plate, and the like.
The liquid crystal display device has been used in indoor such as in a TV, and for example, has been increasingly used in outdoor mainly for a portable device. For this reason, a liquid crystal display device capable of withstanding high temperature and high humidity has been required to be developed from the related art.
In addition, a demand for the liquid crystal display device to be resistant to severe usage conditions in extensively various purposes has been increased, and annually, durability has been required to be at a higher level than that of the related art.
In addition, recently, the liquid crystal display device has been enlarged and thinned mainly for a TV, and according to this, the optical film which is a constituent member is required to be thin. From the related art, it has been important for the optical film to have suitable hardness and excellent cutting properties from a viewpoint of workability, and the thinned optical film is further required to have improved hardness and cutting properties.
In the optical film using the cellulose acylate film, it has been known that a specific compound is contained in the film in order to solve various problems in further improving performance, in properties as the optical film, or in manufacturing.
For example, in order to suppress a variation in retardation of the optical film due to environment humidity, an aliphatic monocarboxylic acid or an aromatic monocarboxylic acid, or an organic phosphoric acid, which has pKa of 2 to 7 (refer to JP2011-118135A) has been proposed, and in order to enhance peelability of a film obtained from a support body at the time of manufacturing a resin film by solvent casting methods and to enhance polarizer durability, it has been proposed that an iminodiacetic acid type organic carboxylic acid compound having two carboxy groups (the value of the pKa is less than or equal to 5.5) is contained in the optical film (refer to JP2012-72348A).